CLS :font 1
GBLX=1000:GBLY=1000
Xres=MM.HRes:Xstp=Xres/GBLX
Yres=MM.VRes:Ystp=Yres/GBLY
MP%=0
open "ctest.svg" for Input as #1
dim integer sc=1,x=0,y=0,XA=1,YA=1,XB1,XB2,YB1,YB2,fn
dim p%(127,2)
'testcurve
do
line input #1,a$:a$=decomma$(a$)
if MP% then
  draw_path (a$)
end if
if left$(a$,5)="<path" then MP%=1
loop until eof(#1)
close #1

Sub draw_path(PTH$)
Local last$=""
Do
cm$=left$(PTH$,1):pth$=lcut$(pth$,1)
Select Case cm$
case "z"
last$=""
exit sub
Case "M"
last$="M"
fn=Instr(pth$," "):XA=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
fn=Instr(1,pth$," "):YA=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
Case "l"
last$="l"
fn=Instr(pth$," "):X=int(.5+val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
fn=Instr(pth$," "):Y=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
Line XA*xstp,YA*ystp,(XA+x)*xstp,(YA+y)*ystp:XA=X:YA=Y
Case "C"
Last$="C"
fn=Instr(pth$," "):tmp$=left$(pth$,fn)
XB1=int(.5+Val(tmp$)):pth$=lcut$(pth$,fn)
fn=Instr(pth$," "):YB1=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
fn=Instr(pth$," "):XB2=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
fn=Instr(pth$," "):YB2=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
fn=Instr(pth$," "):X=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
fn=Instr(pth$," "):Y=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
beziercubic XA,YA,XB1,YB1,XB2,YB2,X,Y,40
XA=X:YA=Y
Case Else
Select Case last$
Case "l"
fn=Instr(pth$," "):Y=Val(left$(pth$,fn)):pth$=lcut$(pth$,fn)
Line XA*xstp,YA*ystp,(XA+x)*xstp,(YA+y)*ystp:XA=X:YA=Y
Case "C1"
fn=Instr(pth$," "):tmp$=left$(pth$,fn)
XB1=int(.5+Val(tmp$)):pth$=lcut$(pth$,fn)
fn=Instr(pth$," "):YB1=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
fn=Instr(pth$," "):XB2=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
fn=Instr(pth$," "):YB2=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
fn=Instr(pth$," "):X=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
fn=Instr(pth$," "):Y=int(.5+Val(left$(pth$,fn))):pth$=lcut$(pth$,fn)
beziercubic XA,YA,XB1,YB1,XB2,YB2,X,Y,40
XA=X:YA=Y
End Select
End Select
if pth$="" then line input #1,a$:pth$=decomma$(a$)
if eof (#1) then exit do
Loop
End Sub
'
function lcut$(in$,num%)
if len(in$) <1 then lcut$="" else lcut$=right$(in$,len(in$)-num%)
end function
'
function decomma$(ein$)
   local fn=0
   do
       fn=instr(ein$,",")
       if not fn then exit do
       mid$(ein$,fn,1)=" "
   loop
   decomma$=ein$
end function

'---------------
'Translation of the BBC Version
'https://rosettacode.org/wiki/Bitmap/B%C3%A9zier_curves/Cubic#BBC_BASIC
Sub beziercubic(x1%,y1%,x2%,y2%,x3%,y3%,x4%,y4%,n%)
 Local i%,t,t1,a,b1,c,d
 For i%=0 To n%
   t=i%/n%:t1=1-t:a=t1^3:b=3*t*t1^2:c=3*t^2*t1:d=t^3
   p%(i%,1)=INT(a*x1%+b*x2%+c*x3%+d*x4%+.5)
   p%(i%,2)=INT(a*y1%+b*y2%+c*y3%+d*y4%+.5)
 Next
 For i%=0 To n%-1
   line p%(i%,1),p%(i%,2),p%(i%+1,1),p%(i%+1,2)
 Next
End Sub
'Translation of the BBC Version
'https://rosettacode.org/wiki/Bitmap/B%C3%A9zier_curves/Quadratic#BBC_BASIC
sub bezierquad(x1%,y1%,X2%,y2%,X3%,y3%,n%)
 Local i%, t, t1, a, b, c, p%(n%,2)
 For i%=0 To n%
   t=i%/n%:t1=1-t:a=t1^2:b=2*t*t1:c=t^2
   p%(i%,1)= INT(a*x1%+b*X2%+c*X3%+.5)
   p%(i%,2)= INT(a*y1%+b*y2%+c*y3%+.5)
 Next
 For i%=0 To n%-1
   line p%(i%,1),p%(i%,2),p%(i%+1,1),p%(i%+1,2)
 Next
end sub